Ignition magneto



Nov. 16, 1948.

H. T. HEAL IGNITION MAGNETO Filed Jan. 4, 1945 INVENTOR.

ATTORNEY Patented Nov. 16, 1948 IGNITION MAGNE'IO Henry Thomas Heal,London, England; assignor to Rotax Limited, London, EnglandApplicationJanuary 4, 1945', Serial No. 571,337 In Great BritainDecember 1, 1943 Section 1, Public Iiaw 690, August 8, 1946 Patentexpires December 1, 1963 9 Claims.

This invention relates to ignition magnetos for internal combustionengines, and particularly aircraft engines, the object of the inventionbeing to provide simple and satisfactory means for re'-' stricting theduration of each. of the successive high tension spark discharges.

. The invention consists of the combination with. the primary winding(or each such winding) of:

a small inductive winding connected in parallel with the make-and-breakdevice.

The invention also consists in the combination with the inductivewinding of a non-inductive resistance arranged in series therewith.

Moreover, the invention comprises the combination with the inductivewinding (and series resistance when the latter is used), of anautomatic, device for controlling the connection of this wind-I- ing orwinding and resistance with the primary winding.

In the accompanying sheet of explanatory diagrams Figure 1 illustratesone mode of carrying the. invention into efiect.

Figures 2 and 3 illustrate respectively two modified features of theinvention.

In Figure l (1 indicates an ignition magneto provided with the usualspark generator and distributor. The spark generator comprises a primarywinding b, a secondary winding 0, a condenser d, and a make-and-breakdevice e, the condenser and make-and-break device being connected inparallel with each other and with the primary winding. The distributorcomprises a rotary contact arm connected to the secondary winding 0, andfixed contacts as g over which the arm is movable.

In applying the invention to the magneto illustrated in Figure 1, Iconnect a small inductive Winding h across the ends of the primarywinding 1) and in parallel with the make-andbreak device 6. It isimpossible to specify in general terms, the most suitable amount ofinductance required in the winding h, as this will vary with the sizeand design of the magneto a, but the optimum value can very readily beascertained by trial, the object in view being that of reducing theduration of the spark discharge to what is considered to besatisfactory.

When the amount of energy to be dissipated is relatively large it may beadvantageous to arrange in series with the inductive winding h anoninductive resistance 2' as illustrated in Figure 2. Thisnon-inductive resistance may be mounted on the inductive winding h, andits optimum Value can readily be ascertained by trial.

2 When the invention is applied to'magnetos for aircraft engines, it maybe unnecessary or undesirable to have the inductive winding (or the.inductive winding and the non-inductive resistance when the latter isemployed) in continual; For example, it may be required'that the use.controlof spark duration shall be operative only, when flying at highaltitudes. To meet this or any other allied condition I employ any con.-

venient automatic switch for putting the said,

winding or winding and resistance in orout' of action, this switch beingresponsive to barometric:

pressure or other appropriate conditions. As. illustrated in Figure 3,such a switch may con"- sist ofa pair of complementary (fixed andmovable) contacts 7', arranged in series with the:

windings h, 2', a resilient member m carrying the? movable contactlaandan evacuatedcapsule n1 connected by astem 0 to the resilient member andarranged in a container p communicating with the atmosphere, thearrangement beingsuch.

that the movable contact is responsive to barometric conditions.

By this invention the required control of the duration of each of thehigh tension spark discharges of the magneto can be effected in a verysimple and satisfactory manner and without unduly impairing theefficiency of the magneto.

When the invention is applied to a magneto having more than one primarywinding, an inductive winding (and if desired a non-inductiveresistance) as above described may be associated with each primarywinding.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. In a sparking apparatus of the type having a coil comprising primaryand secondary windings and a make and break device connected across saidprimary winding, the improvement that comprises means for limiting theduration of the sparks under atmospheric conditions of relatively lowpressure comprising an inductive winding and a non-inductive resistancein series, and means operable by changes in atmospheric pressure toconnect the said series in parallel with the make and break device whenthe atmospheric pressure decreases, and to break the connection when theatmospheric pressure increases.

2. In a sparking device of the type having a coil comprising primary andsecondary windings and a make and break device connected across saidprimary winding, the sparks of which are affected by changes insurrounding atmospheric condi tions, the improvement that comprisesmeans for 3 limiting the duration of the sparks under atmosphericconditions of relatively low pressure comprisin an inductive winding,and means operable by changes in atmospheric pressure to connect thesaid inductive winding in parallel with the said make and break devicewhen the atmospheric pressure decreases and to break the connection whenthe atmospheric pressure increases.

3. In a sparking device of the type having a coil with primary andsecondary windings and a make and break device, the sparks of which areaffected in their operative eiiect by surrounding conditions, theimprovement that comprises means for limiting the duration of the sparkwhen said affecting surrounding conditions are changed comprisin aninductance, and means operable by said changes in said surroundingconditions to connect the said inductance in parallel with the said makeand break device when a said change of one type occurs, and to break theconnection when an opposite change occurs.

4. In a sparking device of the type having a primary windin and a makeand break device, the sparks of which are afiected in their operativeeffect by surrounding conditions, the improvement that comprises meansfor limiting the duratiton of the spark when said affecting surroundingconditions are changed comprising an inductance, and means operable bysaid changes in said surrounding conditions to connect the saidinductance in parallel to the said make and break device when a saidchange of one type occurs, and to break the connection when an oppositechange occurs.

5. Apparatus for controlling the duration of a magneto spark includingan inductance, smaller than those of the generator and transformerwindings of the magneto, connected in parallel to the make and breakdevice of the magneto.

6. Apparatus for controlling the duration of a magneto spark includingan inductance, smaller than those of the generator and transformerwindings of the magneto, connected in series with a non-inductiveresistance and in parallel with the make and break device of themagneto.

7. Apparatus for controlling the duration of a spark from a transformercoil including a transformer coil, a make and break device in paralleltherewith, an inductance smaller than the inductance of the transformercoil connected in parallel therewith, a current controlling meansbetween the said inductance and the said make and break device, andatmospheric pressure operated means operatively connected to the currentcontrolling means. 8. A magneto ignition device having the make andbreak device of the magneto, and a small inductive winding connected inparallel across the primary winding of the magneto transformer andincluding pressure-sensitive means for making and breaking theconnection of said inductive winding with the primary winding inresponse to variations in circumambient pressure.

9. A magneto ignition device having the make and break device of themagneto, and a small inductive winding connected in parallel across theprimary winding of the magneto transformer and including meanscomprising a diaphragm responsive to changes in atmospheric pressure formaking and breaking the connection of the inductive winding with themake and break device.

HENRY THOMAS HEAL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,224,24l Wacker May 1, 19171,640,936 Hawkins Aug, 30, 1927 2,007,373 Kongsted July 9, 19352,090,365 Harris Aug. 17, 1937 2,117,422 Holthouse May 17, 19382,196,693 Blake Apr. 9, 1940 2,292,809 Welch Aug. 11, 1942

